Write protect switch for card connector

ABSTRACT

The write protect switch SW comprises a first piece of metal ( 50 ) formed from a stationary metal piece and a second piece of metal ( 40 ). The touching portion ( 46 ) of the second piece of metal ( 40 ) that comes in contact with one of the slide positions of the write protect button ( 3 ) in the recess ( 2 ) is situated generally at the center position between the contact portion ( 45 ) and the holding portion ( 42 ) of the second piece of metal ( 40 ) or on the holding portion ( 42 ) side of the center position. This arrangement ensures a reliable, stable separably connecting operation of the two pieces of metal ( 40, 50 ) and provides a necessary contact pressure between them so that the position of the write protect button ( 3 ) can be detected accurately and reliably.

TECHNICAL FILED

The present invention relates to a card connector mounted on electronicdevices, such as cellular phones, telephones, PDA (personal digitalassistants), portable audio devices and digital cameras, and morespecifically to a write protect switch for detecting a position of awrite protect button on an IC card.

BACKGROUND ART

In electronic devices such as cellular phones, telephones, PDA anddigital cameras, addition of a variety of functions and identificationof a user are made by inserting an IC card with a built-in IC, such as aSIM (subscriber identity module) card, an MMC (multimedia card) (trademark), a smart media (trade mark) and an SD (secure digital or superdensity) card.

The IC card of this kind normally has some means for inhibiting thewrite operation in order to protect information stored in its internalmemory. A means is also provided to cancel the write protection to allowinformation to be written from an electronic device. into the memory ofthe IC card when the card holder so desires.

Various kinds of write protect methods have been proposed. One suchmeans is a mode of the write protect button that can slide between twopositions, as in a floppy disk. The mode of the write protect button isconsidered advantageous because it can be used repetitively and theconstruction is simple.

In such a slide button system, it is no secret that the card is providedwith a write protect button that can slide between two positions and theelectronic device is provided with an electric circuit which is set to awrite inhibit state when the write protect button is situated at oneposition and to a write-enable state when it is situated at anotherposition.

As a sensor structure for detecting the position of the write protectbutton, a optical sensor structure may be considered. The optical sensorstructure, however, has drawbacks that a sufficient detection precisioncannot be expected as the IC card becomes thinner and smaller and thatthe installation of a optical sensor can hinder promotion in downsizingand cost-reduction.

FIG. 6A and FIG. 6B show the construction of a conventional writeprotect switch using a contact leaf spring.

In this conventional construction, a switch structure having a contactleaf spring 100 with a contact portion 100 a and a stationary leafspring 101, detects the position of a write protect button 102. In thisswitch structure, when the button 102 is situated at one position, theleaf springs 100, the stationary leaf 101 are parted (FIG. 6A); and whenthe button 102 is at the other position, a contact portion 100 a of thecontact leaf 100, stationary leaf 101 are connected (FIG. 6B).

In such a switch structure, the displacement of the contact leaf 100basically depends on the height (thickness) of the button 102. Theconnector and card have variations in dimensional error and there areparts and assembly tolerances. Thus, the actual displacement of thecontact leaf spring 100 is obtained by subtracting the above-describederrors from the thickness of the button 102.

In many cases, the displacement of the contact leaf 100 is often notenough for button 102 detection.

Further, in the conventional technique described above, the elasticallydeflecting contact leaf spring 100 is constructed such that thedifference between a length D and a length E is small, the length Dbeing measured from a fixed portion 100 b, which fixedly supports thecontact leaf spring like a cantilever, to the engagement portion 100 cthat engages the write protect button 102, the length E being measuredfrom the fixed portion 100 b to the contact portion 100 a. Thus, thedeflection obtained at the contact portion 100 a is not greater than adeflection produced at the engagement portion 100 c. This is combinedwith the above-described problem of error and assembly tolerances,making it impossible to secure a sufficient contact pressure of thecontact portion 100 a for making an electric connection. In the worstcase, it is a problem since the position of the write protect button 102may not be able to be detected stably and accurately.

The present invention has been accomplished under these circumstances.It is an object of the invention to provide a write protect switch for acard connector that can perform reliable and stable separably connectingoperations of metal leaf springs and which can provide a necessarycontact pressure of the contact portion for reliable electric connectionbetween the two metal leaf springs.

DISCLOSURE OF INVENTION

According to one aspect, the present invention provides a write protectswitch in a card connector for detecting a slide position of a writeprotect button on a card, wherein when the card having the write protectbutton of a predetermined height, which is slidable between twopositions in a recess formed in an outer surface of the card, is loadedinto the card connector, the write protect switch detects the slideposition of the write protect button on the card according to anseparably connecting of a pair of pieces of metal, the write protectswitch comprising: a first piece of metal made from a stationary pieceof metal; and a cantilevered second piece of metal having a holdingportion at one end side thereof and a contact portion at the other endside thereof, the holding portion being rigidly held in a housing of thecard connector, the contact portion being connected or separated withthe first piece of metal, the second piece of metal also having aprojecting touching portion between the holding portion and the contactportion, the projecting touching portion being adapted to touching oneof the slide position of the write protect button in the recess; whereinthe projecting touching portion is situated generally at a centerposition between the contact portion and the holding portion or on theholding portion side of the center position.

In the cantilevered metal leaf spring, one of the pieces of metal makingup the write protect switch, the projecting touching portion that comesin contact with the write protect button is situated generally at thecenter position between the contact portion and the holding portion ofthe metal leaf spring, i.e., at the center position between the ends ofthe metal leaf spring, or on the holding portion side of the centerposition. With this write protect switch, therefore, the two metalpieces can be connected or separated by a displacement of the contactportion which is at least two times the height of the write protectbutton.

Thus, if various error factors exist, this invention enables a reliable,stable separably connecting of the two pieces of metal and provides anenough contact pressure to make electrical connection.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view showing an example of an IC card to be insertedinto a card connector of this invention.

FIG. 2 is a horizontal cross section showing an internal structure ofthe card connector when the card is unloaded.

FIG. 3 is a horizontal cross section showing the internal structure ofthe card connector when a write-enabled card is inserted.

FIG. 4 is a horizontal cross section showing the internal structure ofthe card connector when a write inhibited card is inserted.

FIG. 5 is a horizontal cross section showing the working principle ofthe write protect switch.

FIG. 6A and FIG. 6B are schematic diagrams showing a conventionaltechnique, with FIG. 6A representing a state when the write protectswitch is OFF and FIG. 6B representing a state when the write protectswitch is ON.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, embodiments of this invention will be described in detail byreferring to the accompanying drawings.

FIG. 1 is a plan view of an example of IC card to be loaded into thecard connector of this invention.

The IC card 1 has a notch(recess) 2 formed at one side, in which a writeprotect button 3 is arranged slidable in a card insertion and removedirection (direction of arrow A). The write protect button 3 can be slidto one of two positions: a protect-on position (write inhibit position)indicated by a solid line and a protect-off position (write enableposition) indicated by a chain doubled-dashed line.

When the button 3 is set to a rear side portion 2 b in the recess 2, theIC card 1 is write inhibited. When the button 3 is set to a front sideportion 2 a in the recess 2, the IC card 1 is write-enabled. The backsurface of the card 1 is provided with a plurality of contact pads 4indicated by dashed lines which are designed to make contact withcontact terminals (not shown in FIG. 1) on the card connector side,including a power supply terminals and signal terminals. The IC card 1has a notch portion 5 at one front corner for preventing a possibleerroneous insertion.

FIGS. 2-4 show a cross-sectional structure of the card connector 10 thatreceives an IC card 1. FIG. 2 represents a state when the card 1 is notyet loaded; and FIG. 3 and FIG. 4 represent states when the card 1 isloaded. In FIG. 3 the write protect button 3 is at the write enableposition. In FIG. 4 the write protect button 3 is at the write inhibitposition.

The card connector 10 shown in FIGS. 2-4 is mounted on electronicdevices, such as cellular phones, PDA, portable audio devices anddigital cameras.

The card connector 10 has an integrally molded connector housing 20 madeof an insulating material such as resin. The connector housing 20 issecured to a printed circuit board by a pair of fixing metal 50 at theleft and right side.

The IC card 1 is inserted into the card connector 10 through a cardinsertion opening 21 formed at the front of the connector housing 20.

The connector housing 20, as shown in FIG. 2, is provided with aabutment wall 22 against which the inserted IC card 1 is pushed. At onecorner of the abutment wall 22, the housing 22 is provided with aprojecting corner wall 23 that the notch portion 5 of the IC card 1 isapplied.

The IC card 1 is supported at its both side edges by a pair of guidegrooves 24 formed in both inner side walls of the connector housing 20and is guided in the insertion and remove direction. A base plate 25that forms a lower wall of the connector housing 20 has a plurality ofpress-fit grooves 31 in which a plurality of cantilevered contactterminals 30 are positioned and press-fitted.

Each of contact terminals 30 include power supply terminals and signalterminals. Each of contact terminals 30 have a terminal portion 30 asoldered joint to a contact pad or the like on the printed circuit boardof the electronic device, a stationary portion 30 b press-fitted in thepress-fit groove 31, and a contact leaf portion 30 c elasticallydeflected to engage the contact pad 4 of the IC card 1. The contactleafportion 30 c has a contact portion 30 d protruding in arc.

These contact terminals 30 make electrical connection between the ICcard 1 and the electronic device and their elastic force provides anappropriate card retaining force when the card is loaded.

One side wall portion 26 of the connector housing 20 is provided with awrite protect switch SW comprising a pair of pieces of metal 40, 50.This write protect switch SW detects the position of the write protectbutton 3 of the IC card 1.

One of the piece of metal, a long metal leaf spring 40, has a terminalportion 41 soldered to the contact pad of the printed circuit board, astationary portion (holding portion) 42 press-fitted in the connectorhousing 20, a leaf portion 43 extending along the side of the insertedcard 1, and a contact portion 45 provided with a raised contactprojection 44. The stationary portion 42 is rigidly secured therebysupporting the metal leaf spring 40 like a cantilever.

Further, the spring portion 43 of the metal leaf spring 40 has antouching portion (projecting portion) 46 projecting at generally thecenter thereof to come in contact with the write protect button 3 or thebottom of the recess 2 of the card 1.

The other piece of metal 50 is a stationary metal terminal having acontact portion 51 with which the contact projection 44 of the matingthe piece of metal 40 is separably connected. In this case, one metalterminal forming the write protect switch SW is also used as one of thefixing metal 50 for securing the connector housing 20 to the printedcircuit board.

As shown in FIG. 3, when the write protect button 3 is at the writeenable position, the projecting portion 46 of the metal leaf spring 40comes in contact with the write protect button 3 slid to the front sideportion 2 a of the recess 2 of the IC card 1. At this time, the contactportion 45 of the metal leaf spring 40 comes in contact with thestationary metal piece 50, turning on the switch SW.

When on the other hand the write protect button 3 is at the writeinhibit position as shown in FIG. 4, the projecting engagement portion46 of the metal leaf spring 40 engages the bottom surface of the frontside portion 2 a of the recess 2 of the card 1. At this time, thecontact portion 45 of the metal leaf spring 40 is parted from thestationary metal piece 50, turning off the switch SW.

In this switch structure because the contact portion 45 of one piece ofmetal 40 comes into or out of contact with the stationary metal piece 50according to the position of the write protect button 3, it is possibleto determine at which position, the write inhibit position or the writeenable position, the write protect button 3 of the IC card 1 is situatedby electrically detecting the connection or disconnection of these metalpieces 40, 50 by an electric circuit connected to the terminal portionsof these metal pieces 40, 50.

In this embodiment, the projecting portion 46 of the metal leaf spring40 or elastically displaceable metal piece that comes in contact witheither the write protect button 3 or the bottom of the notch(recess) 2is situated at generally the center position between the contact portion45 and the stationary portion 42 or on the stationary portion 42 side ofthis center position. In other words, as shown in FIG. 5, a length L1from the stationary portion 42 to the contact portion 45 is set to morethan two times a distance L2 from the stationary portion 42 to theprojecting portion 46.

Therefore, in this embodiment, when the projecting portion 46 iselastically displaced by an amount B according to the position of thewrite protect button 3, the contact portion 45 at the free end of themetal leaf spring 40 is reliably displaced by more than two times theamount B (2×amount B), as shown in FIG. 5.

In this switch structure, as described above, the contact portion 45 ofthe metal leaf spring 40 can be displaced by more than two times theheight or thickness of the write protect button 3. By this enlargeddisplacement the mating metal pieces 40, 50 can be connected orseparated.

Hence, even when there are various error factors, including dimensionaltolerances of the card and of the card support portion of the connectorand dimensional variations during manufacture, this switch structure canassure reliable and stable connection and separateness of the matingpieces of metal 40,50 and provide a sufficient contact pressure to makeelectrical connect with each other. This in turn enables a precise,reliable detection at all times of the position of the write protectbutton 3, reliably preventing an erroneous operation of writing into thewrite inhibited IC card 1.

While in the embodiment described above the button position indicated bya solid line in FIG. 1 represents the write inhibit position and theposition indicated by a chain doubled-dashed line represents the writeenable position, they may be reversed, i.e., the button positionindicated by a solid line of FIG. 1 may be used as the write enableposition and the position indicated by a chain doubled-dashed line asthe write inhibit position.

Further, although in the embodiment above one of the mating pieces ofmeta 150, of the write protect switch SW is also used as the fixingmetal to secure the card connector 10 to the printed circuit board, thepiece of metal 50 and the fixing metal may be formed as separatecomponents.

Further, although in the embodiment above the stationary portion 42 ofthe metal leaf spring 40 is arranged on the front end side of theinserted IC card 1 (on the far side of the connector), the direction ofthe metal leaf spring 40 may be reversed by a 180-degree angle to putthe stationary portion 42 on the rear end side of the IC card 1 (on thenear side of the connector).

Further, while in the embodiment above the projecting engagement portion46 of the metal leaf spring 40 is made to come in contact with thebottom of the front side portion 2 a of the recess 2 of the IC card 1,it may be made to come in contact with the bottom of the rear sideportion 2 b.

Further, while in the embodiment above the write protect switch SW isarranged in the side wall portion of the connector housing 20 to matchthe card having the write protect button 3 at its side, when the cardhas the write protect button at the front, on the surface or on the backof the card, the position of the write protect switch SW need only bechanged accordingly.

INDUSTRIAL APPLICABILITY

As described above, one of the pieces of metal making up the writeprotect switch, namely the cantilevered metal leaf spring, isconstructed such that the touching portion touching the write protectbutton is situated generally at the center position between the contactportion and the holding portion of the metal leaf spring, i.e., at thecenter position between the ends of the metal leaf spring, or on theholding portion side of this center position. This arrangement displacesthe contact portion of the metal leaf spring by at least two times theheight or thickness of the write protect button when the pair of piecesof metal making up the write protect button are connected or separatedeach other.

Therefore, in a small or very small card that cannot provide an enoughspace for the height of the button, even when various error factors areproduced, the switch structure described above can ensure a reliableconnection or separateness operation of the contact leaf and provide asufficient contact pressure to make an electrical contact. It istherefore possible to precisely and reliably detect the position of thewrite protect button at all times, preventing a possible error ofwriting data into a write inhibited card.

What is claimed is:
 1. A write protect switch in a card connector fordetecting a slide position of a write protect button on a card, whereinwhen said card having said write protect button of a predeterminedheight, which is slidable between two positions in a recess formed in anouter surface of said card, is loaded into said card connector, thewrite protect switch detects the slide position of the write protectbutton on the card according to an connection or separateness of a pairof pieces of metal, said write protect switch comprising: a first pieceof metal made from a stationary piece of metal wherein said first pieceof metal also serves as a fixing metal for fixing a housing of said cardconnector to a printed circuit board; and a cantilevered second piece ofmetal having a holding portion at one end side thereof and a contactportion at the other end side thereof, said holding portion beingrigidly held in a housing of said card connector, said contact portionbeing separably connected with said first piece of metal, saidcantilevered second piece of metal also having a projecting portionbetween said holding portion and said contact portion, said projectingportion being adapted to come in contact with the recess; wherein saidprojecting portion is situated generally at a center position betweensaid contact portion and said holding portion or on said holding portionside of said center position.
 2. A write protect switch in a cardconnector according to claim 1, wherein said write protect switch isarranged in a side wall portion of the connector housing.